Systems and methods for mapping dmrs configuration to phase noise tracking pilot for improved receiver performance

ABSTRACT

According to certain embodiments, a user equipment (810) is provided for use in a cellular network. The user equipment (810) may include a transceiver (910), a processor (920), and a memory (930). The user equipment (810) may be configured to acquire a Demodulation Reference Signal (DMRS) configuration. A mapping is determined from the DMRS configuration to a phase noise tracking reference signal (PNT-RS). A channel estimate is performed using the DMRS configuration. Phase noise estimation and compensation is performed based on the PNT-RS by using the mapping and the channel estimate.

PRIORITY

This application claims priority to U.S. Patent Provisional ApplicationNo. 62/292,921 filed on Feb. 9, 2017, entitled “Systems and Methods forMapping DMRS Configuration to Phase Noise Tracking Pilot for ImprovedReceiver Performance,” the disclosure of which is hereby incorporated byreference.

TECHNICAL FIELD

The present disclosure relates, in general, to wireless communicationsand, more particularly, to mapping DMRS configuration to phase noisetracking pilot for improved receiver performance.

BACKGROUND

Communications between a transmitter and receiver generally require someform of synchronization in time and/or frequency before transmissions ofmessages can be received reliably. In cellular systems such as Long TermEvolution (LTE), base stations regularly broadcast narrowbandsynchronization signals regularly in time from which wireless devicesaccessing the system can perform an initial cell search, i.e. goingthrough a synchronization procedure that includes finding carrierfrequency, time reference instants and cell identity. An LTE wirelessdevice that has performed initial cell search and identified the cellidentity can then complete the initial synchronization in downlink bymaking a fine synchronization on cell specific reference signals thatare transmitted over the system bandwidth and more frequently in timethan the synchronization signals. The wireless device connects to thenetwork via a random access procedure in which uplink timesynchronization will be established and communications between thedevice and the base station can begin. Due to oscillator drifting atboth transmitter and receiver sides, the wireless device needs toregularly perform fine frequency synchronization in downlink during thecommunications with the base station.

A lean frame structure design for NX without cell specific referencesignals (CRS) has been proposed where instead reference signals requiredfor fine synchronization and demodulation of a downlink (DL) physicaldata channel (PDCH) are embedded into the PDCH transmission. FIG. 1illustrates the DL transmissions of PDCH and associated DL physicaldownlink control channel (PDCCH), carrying an assignment or a grant.More specifically, FIG. 1 illustrates that the first OrthogonalFrequency Division Multiplexing (OFDM) symbol of a subframe containsPDCCH and following OFDM symbols contain PDCHs.

As also illustrated in FIG. 1, transmissions of PDCH may span overmultiple subframes in the case of subframe aggregation or be confined toone subframe. A wireless device, which may also be referred to as userequipment (UE), detects PDCCH addressed to the UE and derives from thescheduling information PDCH related information. A UE is not aware ofPDCCH transmissions to other UEs where a PDCCH to one particular user iscarried on a subset of OFDM subcarriers. The mapping of PDCCH can eitherbe distributed or localized with latter being illustrated in FIG. 1. Thenumber of OFDM symbols within a subframe is a system design parameterand may very well be larger than the 4 used in the depicted example.

In the illustrated example, PDCCH and PDCH have their own referencesignals for demodulation which mainly refer to Demodulation ReferenceSignals (DMRS) but could potentially also refer to other types ofreference signals as will be discussed herein. The DMRS should betransmitted early in the subframe to enable the receiver to performearly channel estimation and by that reduce receiver processing time.

In the context of NX, time-synchronization is done using a firstreference signal (e.g., a Time Synchronization Signal (TSS)) andcoarse-frequency-sync using the same first reference signal or a secondsignal (e.g., Frequency Synchronization Signal). One may observe thatthese signals are not intended to provide a very accuratesynchronization, neither in time nor in frequency. The time-error can behandled by the cyclic-prefix in an OFDM system and the frequency errorby having sufficient sub-carrier spacing. However, in order to not limitthe performance of higher rank transmissions of PDCH in conjunction withhigher modulation (such as 64 and 256 QAM) schemes, betterfrequency-synchronization is needed. State of the art solutions (e.g. asin LTE) reuse DMRS or CRS for this purpose.

In 5G system deployments at higher carrier frequencies, the radio linkwill exhibit some new properties compared to LTE at lower carrierfrequencies. One of the fundamental changes is that the phase noiseproblem is scaled with frequency which introduces a need for a new phasereference signal to mitigate phase noise that is common for allsubcarriers within an OFDM symbol. This reference signal may be neededboth in uplink and downlink. It is foreseen that this signal can be usedfor both fine carrier frequency-synchronization and phase noisecompensation. Where the second is the focus, the reference signal may bereferred to as the Phase Noise Tracking Reference Signal (PNT-RS).

FIG. 2 illustrates an example time-frequency grid containing DMRS andphase noise tracking RS. The illustrated design is just one examplesince the design has not yet been specified in 3GPP. As depicted, thereference signal is transmitted time continuously and a length 8cover-code is assumed to be used to create 8 orthogonal DMRS resources.The DMRS resource can be enumerated 0 . . . 7 and can be considered tobe 8 DMRS ports.

In a traditional synchronized radio system, such as, for example, LTE,some signals are always present to allow the UE to find the signalswithout having to communicate with the network first. Examples of suchsignals include Primary Synchronization Signal (PSS), SecondarySynchronization Signal (SSS), and CRS. These types of signals allow theUE to keep time-frequency sync with the network. However, the always-onsignals add some complexity to the radio system, result in bad energyperformance, and provide constant interference.

Some more recent solutions include a lean system design that removessaid signals from the radio system. A problem with these designs is thatthe sync-procedure becomes more complicated and overhead increases. Forexample, phase noise tracking RSs may use a large fraction of thespectrum at the cost of decreased data rates. As another example,reusing DMRS is inefficient as the needed time-density is high foraccurate phase noise tracking. The DMRS design takes frequencyselectivity into account, implying that the resource density infrequency needs to be rather high for demodulation performance. Thus, ifthe same signal is used for both demodulation and phase noise tracking,unnecessary high overhead may be created.

SUMMARY

To address the foregoing problems with existing solutions, disclosed ismethods and systems for Demodulation Reference Signal (DMRS) mapping tophase noise tracking pilot for improved receiver performance.

According to certain embodiments, a user equipment is provided for usein a cellular network. The user equipment may include a transceiver, aprocessor, and a memory. The user equipment may be configured to acquirea Demodulation Reference Signal (DMRS) configuration. A mapping isdetermined from the DMRS configuration to a phase noise trackingreference signal (PNT-RS). A channel estimate is performed using theDMRS configuration. Phase noise estimation and compensation is performedbased on the PNT-RS by using the mapping and the channel estimate.

According to certain embodiments, a method by a user equipment isprovided for use in a cellular network. The method includes acquiring aDemodulation Reference Signal (DMRS) configuration. A mapping isdetermined from the DMRS configuration to a phase noise trackingreference signal (PNT-RS). A channel estimate is performed using theDMRS configuration. Phase noise estimation and compensation is performedbased on the PNT-RS by using the mapping and the channel estimate.

According to certain embodiments, a user equipment is provided for usein a cellular network. The user equipment includes a transceiver, aprocessor, and a memory. The user equipment is configured to send aDemodulation Reference Signal (DMRS) configuration. The DMRSconfiguration is associated with a mapping to a PNT-RS transmission. APNT-RS is transmitted to the receiver according to the mapping.

According to certain embodiments, a method by a user equipment isprovided for use in a cellular network. The method includes sending aDemodulation Reference Signal (DMRS) configuration. The DMRSconfiguration is associated with a mapping to a PNT-RS transmission. APNT-RS is transmitted to the receiver according to the mapping.

According to certain embodiments, a network node is provided for use ina cellular network. The network node includes a transceiver, aprocessor, and a memory. The network node is configured to acquire aDemodulation Reference Signal (DMRS) configuration. A mapping isdetermined from the DMRS configuration to a phase noise trackingreference signal (PNT-RS). A channel estimate is performed using theDMRS configuration. Phase noise estimation and compensation is performedbased on the PNT-RS by using the mapping and the channel estimate.

According to certain embodiments, a method by a network node is providedfor use in a cellular network. The method includes acquiring aDemodulation Reference Signal (DMRS) configuration. A mapping isdetermined from the DMRS configuration to a phase noise trackingreference signal (PNT-RS). A channel estimate is performed using theDMRS configuration. Phase noise estimation and compensation is performedbased on the PNT-RS by using the mapping and the channel estimate.

According to certain embodiments, a network node is provided for use ina cellular network. The network node includes a transceiver, aprocessor, and a memory. The network node is configured to send aDemodulation Reference Signal (DMRS) configuration. The DMRSconfiguration is associated with a mapping to a PNT-RS transmission. APNT-RS is transmitted to the receiver according to the mapping.

According to certain embodiments, a method by a network node is providedfor use in a cellular network. The method includes sending aDemodulation Reference Signal (DMRS) configuration. The DMRSconfiguration is associated with a mapping to a PNT-RS transmission. APNT-RS is transmitted to the receiver according to the mapping.

According to certain embodiments, a method by a receiver is provided foruse in a cellular network. The method includes acquiring a DemodulationReference Signal (DMRS) configuration. A mapping to a PNT-RStransmission from the DMRS configuration is determined. A channelestimate is performed using the DMRS configuration. Phase noiseestimation and compensation is performed based on the PNT-RS by usingthe mapping and the channel estimate.

According to certain embodiments, a receiver is provided for use in acellular network. The receiver includes a transceiver, a transmitter, aprocessor, and a memory. The receiver is configured to acquire aDemodulation Reference Signal (DMRS) configuration and determine amapping to a PNT-RS transmission from the DMRS configuration. A channelestimate is performed using the DMRS configuration. Phase noiseestimation and compensation is performed based on the PNT-RS, using themapping and the channel estimate.

According to certain embodiments, a method by a transmitter is provided.The method includes sending, by the transmitter, a DemodulationReference Signal (DMRS) configuration. The DMRS configuration beingassociated with a mapping to a PNT-RS transmission. A PNT-RS istransmitted to the receiver according to the mapping.

According to certain embodiments, a transmitter is provided for use in acellular network. The transmitter includes a transceiver, a transmitter,a processor, and a memory. The transmitter is configured to send aDemodulation Reference Signal (DMRS) configuration, the DMRSconfiguration being associated with a mapping to a PNT-RS transmission.A PNT-RS is transmitted to the receiver according to the mapping.

Certain embodiments of the present disclosure may provide one or moretechnical advantages. For example, in certain embodiments, overhead maybe reduced for the transmission of the PNT-RS signal for the use-casewith a multi-antenna receiver in uplink or downlink. Consider, forexample, an uplink (UL) or downlink (DL) Multi-User Multiple InputMultiple Output (MU-MIMO) with four or more receiver antennas. If fourusers are multiplexed, four sub-carriers may be used. For example, eachuser may transmit on one sub-carrier and blank the other threesub-carriers. Alternatively, according to the methods described herein,only one sub-carrier may be used and the PNT-RS may be separated usingthe DMRS channel estimate. Accordingly, a technical advantage of certainembodiments may include an overhead reduction of up to seventy-fivepercent. Even where some interference remains and gain is lowered, anoverhead reduction may be expected.

Other advantages may be readily apparent to one having skill in the art.Certain embodiments may have none, some, or all of the recitedadvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the disclosed embodiments and theirfeatures and advantages, reference is now made to the followingdescription, taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is block diagram illustrating downlink transmissions of PhysicalData

Channel (PDCH) and associated Physical Downlink Control Channel (PDCCH)for carrying an assignment or grant;

FIG. 2 is a block diagram illustrating an example time-frequency gridcontaining DMRS and phase noise tracking reference signals (PNT-RS);

FIG. 3 is a flow diagram of an example method for PNT-RS reception by areceiver, in accordance with certain embodiments;

FIG. 4 is a block diagram illustrating an example virtual computingdevice for PNT-RS reception, in accordance with certain embodiments;

FIG. 5 is a flow diagram illustrating an example method for PNT-RStransmission by a transmitter, in accordance with certain embodiments;

FIG. 6 is a block diagram illustrating an example virtual computingdevice for PNT-RS transmission, in accordance with certain embodiments;

FIG. 7 is a block diagram illustrating an example time-frequency gridincluding blanked resource for PNT-RS, in accordance with certainembodiments;

FIG. 8 is a block diagram illustrating another example time-frequencygrid demonstrating PNT-RS interfered by data, in accordance with certainembodiments;

FIG. 9 is a block diagram illustrating another example time-frequencygrid demonstrating PNT-RS interfered by other users PNT-RS, inaccordance with certain embodiments;

FIG. 10 is a block diagram illustrating an example embodiment of anetwork for PNT-RS reception, in accordance with certain embodiments;

FIG. 11 is a block schematic of an exemplary wireless device fortransmission or reception of PNT-RS, in accordance with certainembodiments;

FIG. 12 is a block schematic of an exemplary network node fortransmission or reception of PNT-RS, in accordance with certainembodiments; and

FIG. 13 is a block schematic of an exemplary radio network controller orcore network node, in accordance with certain embodiments.

DETAILED DESCRIPTION

According to certain embodiments, how the PNT-RS is beam-formed inrelation to the DMRS may be implicitly or explicitly signaled. Forexample, the phase noise tracking reference signal (PNT-RS) may bemapped to at least one specific port on the DMRS. For example, in aparticular embodiment, the phase noise tracking reference signal may bemapped to the first DMRS port. As such, the receiver may know that thechannel estimate of the effective channel for said DMRS port representsthe effective channel used to transmit the PNT-RSs. This enables areceiver and corresponding transmitter to optimize the beam-forming ofsaid port to enable a good reception by the receiver. In certainembodiments, the receiver may exploit this optimized beam-forming as theDMRS for different users/layers are orthogonal and have higherprocessing gain than the PNT-RS, which is transmitted with low densityto avoid too large over-head and potentially, in some embodiments,independent estimates are needed in each OFDM symbol.

As a result, PNT-RS reception may be spatially separated fromdata/other-signals (including other PNT-RS). Additionally, receiver gainmay be improved due to the processing gain on DMRS. Thus, certainembodiments enable better reception for a multi-antenna receiver and canbe exploited in different embodiments to enable multiplexing PNT-RS withdata transmitted over the remaining antenna ports and/or other users.Some embodiments may also enable higher PNT-RS reuse.

FIG. 3 is a flow diagram of an example method 100 for PNT-RS receptionby a receiver, in accordance with certain embodiments. In variousembodiments, the receiver may include a wireless device or a networknode, of which exemplary embodiments are described in more detail belowwith respect to FIGS. 10-12.

In certain embodiments, the method begins at step 102 when a DMRSconfiguration is acquired. A mapping to a PNT-RS transmission inrelation to the DMRS configuration is identified at step 104. In aparticular embodiment, the PNT-RS may be mapped to a specific DMRS port.Specifically, and as just one example, the PNT-RS may be mapped to afirst DMRS port.

At step 106, a channel estimate is performed on the DMRS. In certainembodiments, the channel estimate and the mapping may be used todetermine a PNT-RS receiver setting.

In particular embodiments, determining the PNT-RS receiver setting mayinclude calculating PNT-RS receiver weights from the channel estimate.

At step 108, phase noise estimation and compensation is performed basedon the PNT-RS and using the mapping and the channel estimate. In certainembodiments, the phase noise estimation and compensation may beperformed on a received transmission of data symbols. In a particularembodiment, a PNT-RS may be interfered by other data associated withother layers associated with the receiver. The method may includeestimating interference from the other layers based on the known channelfrom DMRS for the other layer and interference cancellation may beperformed. Additionally or alternatively, the PNT-RS may be interferedby a co-scheduled PNT-RS associated with another receiver. The methodmay include acquiring the co-scheduled PNT-RS and a DMRS for theco-scheduled PNT-RS and performing interference cancellation for theco-scheduled PNT-RS.

In certain embodiments, the method for PNT-RS reception as describedabove may be performed by a virtual computing device. FIG. 4 is a blockdiagram illustrating an example virtual computing device 200 for PNT-RSreception, in accordance with certain embodiments. As depicted, virtualcomputing device 200 may include modules for performing steps similar tothose described above with regard to the method illustrated anddescribed in FIG. 3. For example, virtual computing device 200 mayinclude at least one acquiring module 202, a determining module 204, afirst performing module 206, a second performing module 208, and anyother suitable modules for PNT-RS reception. In some embodiments, one ormore of the modules may be implemented by a processor, such as theexemplary processors described below with respect to FIGS. 11 and 12.Additionally, it is recognized that, in certain embodiments, thefunctions of two or more of the various modules described herein may becombined into a single module.

The acquiring module 202 may perform the acquiring functions of virtualcomputing device 200. For example, in certain embodiments, acquiringmodule 202 may acquire a DMRS configuration. In a particular embodiment,acquiring module 202 may receive the DMRS configuration from a networknode. In another embodiment, acquiring module 202 may acquire the DMRSconfiguration from a wireless device.

The determining module 204 may perform the determining functions ofvirtual computing device 200. For example, in certain embodiments,determining module 204 may determine a mapping to a PNT-RS transmissionin relation to the DMRS configuration. In a particular embodiment, forexample, determining module 204 may determine that the PNT-RS is mappedto a specific DMRS port, such as a first DMRS port.

The first performing module 206 may perform one or more of theperforming functions of virtual computing device 200. For example, incertain embodiments, performing module 206 may perform a channelestimate on the DMRS.

The second performing module 208 may perform one or more of theperforming functions of virtual computing device 200. For example, incertain embodiments, second performing module 208 may perform phasenoise estimation and compensation based on the PNT-RS determine a PNT-RSreceiver setting. In a particular embodiment, second performing module208 may perform the phase noise estimation and compensation using themapping and the channel estimate.

Other embodiments of virtual computing device 200 may include additionalcomponents beyond those shown in FIG. 4 that may be responsible forproviding certain aspects of the receiver's functionality, including anyof the functionality described above and/or any additional functionality(including any functionality necessary to support the solutionsdescribed above). The receiver may include components having the samephysical hardware but configured (e.g., via programming) to supportdifferent radio access technologies, or may represent partly or entirelydifferent physical components than those depicted.

FIG. 5 is a flow diagram illustrating an example method 300 for PNT-RStransmission by a transmitter, in accordance with certain embodiments.In various embodiments, the transmitter may include a wireless device ora network node, of which exemplary embodiments are described in moredetail below with respect to FIGS. 10-12.

In certain embodiments, the method begins at step 302 when thetransmitter sends a DMRS configuration. In a particular embodiment, thetransmitter may be network node, which sends a DMRS configuration to awireless device. In another embodiment, the transmitter may be awireless device that sends a DMRS configuration to a network node.

In certain embodiments, the DMRS configuration may be associated with amapping to a PNT-RS transmission. In a particular embodiment, forexample, the PNT-RS may be mapped to a specific DMRS port such as, forexample, the first DMRS port.

At step 304, the transmitter transmits a PNT-RS to the receiveraccording to the mapping. As described above, the receiver may use themapping to determine a PNT-RS receiver setting which may in turn be usedto perform phase noise estimation and compensation, in certainembodiments.

In certain embodiments, the method for PNT-RS transmission as describedabove may be performed by a virtual computing device. FIG. 6 is a blockdiagram illustrating an example virtual computing device 400 for PNT-RStransmission, in accordance with certain embodiments. As depicted,virtual computing device 400 may include modules for performing stepssimilar to those described above with regard to the method illustratedand described in FIG. 5. For example, virtual computing device 400 mayinclude at least a sending module 402, a transmitting module 404, andany other suitable modules for PNT-RS transmission. In some embodiments,one or more of the modules may be implemented by a processor, such asthe exemplary processors described below with respect to FIGS. 11 and12. Additionally, it is recognized that, in certain embodiments, thefunctions of two or more of the various modules described herein may becombined into a single module.

The sending module 402 may perform the sending functions of virtualcomputing device 400. For example, in certain embodiments, sendingmodule 402 may send a DMRS configuration. In a particular embodiment,sending module 402 may send the DMRS configuration to a network node. Inanother embodiment, sending module 402 may send the DMRS configurationto a wireless device. The DMRS configuration may be associated with amapping to a PNT-RS transmission from the DMRS configuration. In aparticular embodiment, for example, the PNT-RS may be mapped to aspecific DMRS port, such as a first DMRS port.

The transmitting module 404 may perform the transmitting functions ofvirtual computing device 400. For example, in certain embodiments,transmitting module 404 may transmit a PNT-RS to the receiver accordingto the mapping. As described above, the receiver may then use themapping to determine a PNT-RS receiver setting which may in turn be usedto perform phase noise estimation and compensation, in certainembodiments.

Other embodiments of virtual computing device 400 may include additionalcomponents beyond those shown in FIG. 6 that may be responsible forproviding certain aspects of the receiver's functionality, including anyof the functionality described above and/or any additional functionality(including any functionality necessary to support the solutionsdescribed above). The receiver may include components having the samephysical hardware but configured (e.g., via programming) to supportdifferent radio access technologies, or may represent partly or entirelydifferent physical components than those depicted.

FIG. 7 illustrates an example time-frequency grids 500A-B includingblanked resource for phase noise tracking RS, in accordance with certainembodiments. More specifically, FIG. 7 illustrates a pair oftime-frequency grids 500A and 500B for two respective receivers. Asdepicted, time-frequency grid 500A includes less than eight orthogonalDMRS 502 and PNT-RS 504. Likewise, time-frequency grid 500B includesless than eight orthogonal DMRS 506, which correspond with DMRS 502 oftime-frequency grid 500A, and PNT-RS 508. However, the resourcesassociated with each of PNT-RS 508 and PNT-RS 504 are blanked so thatthey are only used for the respective PNT-RS. Thus, in the depictedscenario, the PNT-RS is not multiplexed with any other signals.Accordingly, the main purpose of the channel estimate on DMRS is toincrease the receiver gain when receiving PNT-RS. As such, a maximumradio transmission (MRT) receiver may be preferred, in certainembodiments.

FIG. 8 illustrates an example time-frequency grids 600A-B includingphase noise tracking RS interfered by data, in accordance with certainembodiments. More specifically, FIG. 8 illustrates a pair oftime-frequency grids 600A and 600B for two respective receivers. Again,time-frequency grid 600A includes less than eight orthogonal DMRS 502and PNT-RS 604. Time-frequency grid 600B includes less than eightorthogonal DMRS 606, which correspond with DMRS 602 of time-frequencygrid 600A, and a PNT-RS 608. In contrast to FIG. 7, the resources usedfor PNT-RS 604 and 608 are not blanked and as a result are interfered byan interfering data.

In certain embodiments, the interfering signal refers to data from otherlayers from a Single User Multiple Input Multiple Output (SU-MIMO) orfrom Multiple User Multiple Input Multiple Output (MU-MIMO). In thissituation, the receiver may treat interference from the other users asone unknown component and the interference from other layers as a secondcomponent that can be estimated due to the known channel (from DMRS) forthese layers. It may be possible to treat interference from other layersin the same was as other interference. In particular, network assistedinterference cancelation may be possible if the network signals theco-scheduled users either to the wireless device or over the backhaul tothe receiving network nodes.

FIG. 9 illustrates an example time-frequency grids 700A-B includingPNT-RS interfered by other users PNT-RS, in accordance with certainembodiments. More specifically, FIG. 9 illustrates a pair oftime-frequency grids 700A and 700B for two respective receivers. Again,time-frequency grid 700A includes less than eight orthogonal DMRS 702and PNT-RS 704. Time-frequency grid 700B includes less than eightorthogonal DMRS 706, which correspond with DMRS 702 of time-frequencygrid 700A, and a PNT-RS 708.

As depicted PNT-RS 708 and PNT-RS 704 are interfered by an interferingsignal. In some embodiments, the interfering signal refers to the PNT-RSfrom other users. For example, PNT-RS 708 is interfered by PNT-RS 704,and vice versa.

In certain embodiments, the receiver has less interference from theother users as it is assumed that each user only needs one PNT-RSindependent upon the number of layers in the transmission. For example,in some embodiments, there may be less interference on the PNT-RS.Accordingly, in certain embodiment, network-assisted interferencecancelation may be very beneficial since the network can signal not onlythe co-scheduled phase noise tracking RS (if any) but also the relevantDMRS for the co-scheduled synchronization signals. As a result, veryefficient cancelation of the other PNT-RS.

FIG. 10 is a block diagram illustrating an embodiment of a network 800,in accordance with certain embodiments. Network 800 includes one or morewireless devices 810A-C, which may be interchangeably referred to aswireless devices 810 or UEs 810, and network nodes 815A-C, which may beinterchangeably referred to as network nodes 815 or eNodeBs (eNBs) 815.A wireless device 810 may communicate with network nodes 815 over awireless interface. For example, a wireless device 810A may transmitwireless signals to one or more of network nodes 815, and/or receivewireless signals from one or more of network nodes 815. The wirelesssignals may contain voice traffic, data traffic, control signals, and/orany other suitable information. In some embodiments, an area of wirelesssignal coverage associated with a network node 815 may be referred to asa cell. In some embodiments, wireless devices 810 may have D2Dcapability. Thus, wireless devices 810 may be able to receive signalsfrom and/or transmit signals directly to another wireless device. Forexample, wireless device 810A may be able to receive signals from and/ortransmit signals to wireless device 810B.

In certain embodiments, network nodes 815 may interface with a radionetwork controller (not depicted in FIG. 10). The radio networkcontroller may control network nodes 815 and may provide certain radioresource management functions, mobility management functions, and/orother suitable functions. In certain embodiments, the functions of theradio network controller may be included in network node 815. The radionetwork controller may interface with a core network node. In certainembodiments, the radio network controller may interface with the corenetwork node via an interconnecting network. The interconnecting networkmay refer to any interconnecting system capable of transmitting audio,video, signals, data, messages, or any combination of the preceding. Theinterconnecting network may include all or a portion of a publicswitched telephone network (PSTN), a public or private data network, alocal area network (LAN), a metropolitan area network (MAN), a wide areanetwork (WAN), a local, regional, or global communication or computernetwork such as the Internet, a wireline or wireless network, anenterprise intranet, or any other suitable communication link, includingcombinations thereof.

In some embodiments, the core network node may manage the establishmentof communication sessions and various other functionalities for wirelessdevices 810. Wireless devices 810 may exchange certain signals with thecore network node using the non-access stratum layer. In non-accessstratum signaling, signals between wireless devices 810 and the corenetwork node may be transparently passed through the radio accessnetwork. In certain embodiments, network nodes 815 may interface withone or more network nodes over an internode interface. For example,network nodes 815A and 815B may interface over an X2 interface (notdepicted).

As described above, example embodiments of network 800 may include oneor more wireless devices 810, and one or more different types of networknodes capable of communicating (directly or indirectly) with wirelessdevices 810. Wireless device 110 may refer to any type of wirelessdevice capable of communicating with network nodes 815 or anotherwireless device 810 over radio signals. Wireless device 810 may also bea radio communication device, target device, device-to-device (D2D) UE,machine-type-communication UE or UE capable of machine to machinecommunication (M2M), a sensor equipped with UE, iPad, Tablet, mobileterminals, smart phone, laptop embedded equipped (LEE), laptop mountedequipment (LME), USB dongles, Customer Premises Equipment (CPE), etc.Examples of wireless device 110 include a mobile phone, a smart phone, aPDA (Personal Digital Assistant), a portable computer (e.g., laptop,tablet), a sensor, a modem, a machine-type-communication (MTC)device/machine-to-machine (M2M) device, laptop embedded equipment (LEE),laptop mounted equipment (LME), USB dongles, a D2D capable device, oranother device that can provide wireless communication. A wirelessdevice 110 may also be referred to as UE, a station (STA), a device, ora terminal in some embodiments. Also, in some embodiments genericterminology, “radio network node” (or simply “network node”) is used. Itcan be any kind of network node, which may comprise a Node B, basestation (BS), multi-standard radio (MSR) radio node such as MSR BS,eNode B, network controller, radio network controller (RNC), basestation controller (BSC), relay donor node controlling relay, basetransceiver station (BTS), access point (AP), transmission points,transmission nodes, RRU, RRH, nodes in distributed antenna system (DAS),core network node (e.g. MSC, MME etc), O&M, OSS, SON, positioning node(e.g. E-SMLC), MDT, or any suitable network node.

The terminology such as network node and UE should be consideringnon-limiting and does in particular not imply a certain hierarchicalrelation between the two; in general “eNodeB” could be considered asdevice 1 and “UE” device 2, and these two devices communicate with eachother over some radio channel. Example embodiments of wireless devices810, network nodes 815, and other network nodes (such as radio networkcontroller or core network node) are described in more detail withrespect to FIGS. 11, 12, and 13, respectively.

Although FIG. 10 illustrates a particular arrangement of network 800,the present disclosure contemplates that the various embodimentsdescribed herein may be applied to a variety of networks having anysuitable configuration. For example, network 800 may include anysuitable number of wireless devices 810 and network nodes 815, as wellas any additional elements suitable to support communication betweenwireless devices or between a wireless device and another communicationdevice (such as a landline telephone). Furthermore, although certainembodiments may be described as implemented in a long term evolution(LTE) network, the embodiments may be implemented in any appropriatetype of telecommunication system supporting any suitable communicationstandards and using any suitable components, and are applicable to anyradio access technology (RAT) or multi-RAT systems in which the wirelessdevice receives and/or transmits signals (e.g., data). For example, thevarious embodiments described herein may be applicable to LTE,LTE-Advanced, LTE-U UMTS, HSPA, GSM, cdma2000, WiMax, WiFi, anothersuitable radio access technology, or any suitable combination of one ormore radio access technologies. Although certain embodiments may bedescribed in the context of wireless transmissions in the downlink, thepresent disclosure contemplates that the various embodiments are equallyapplicable in the uplink and vice versa.

FIG. 11 is a block schematic of an exemplary wireless device 810, inaccordance with certain embodiments. As depicted, wireless device 810includes transceiver 910, processor 920, and memory 930. In someembodiments, transceiver 910 facilitates transmitting wireless signalsto and receiving wireless signals from network node 815 (e.g., via anantenna), processor 920 executes instructions to provide some or all ofthe functionality described above as being provided by wireless device810, and memory 930 stores the instructions executed by processor 920.

Processor 920 may include any suitable combination of hardware andsoftware implemented in one or more modules to execute instructions andmanipulate data to perform some or all of the described functions ofwireless device 810. In some embodiments, processor 920 may include, forexample, one or more computers, one or more central processing units(CPUs), one or more microprocessors, one or more applications, and/orother logic.

Memory 930 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by a processor. Examples of memory 930 includecomputer memory (for example, Random Access Memory (RAM) or Read OnlyMemory (ROM)), mass storage media (for example, a hard disk), removablestorage media (for example, a Compact Disk (CD) or a Digital Video Disk(DVD)), and/or or any other volatile or non-volatile, non-transitorycomputer-readable and/or computer-executable memory devices that storeinformation.

Other embodiments of wireless device 810 may include additionalcomponents beyond those shown in FIG. 11 that may be responsible forproviding certain aspects of the wireless device's functionality,including any of the functionality described above and/or any additionalfunctionality (including any functionality necessary to support thesolution described above). In certain embodiments, for example, wirelessdevice 810 may include components for performing the reception methoddiscussed above with regard to FIG. 3 and/or the transmission methoddiscussed above with regard to FIG. 5.

FIG. 12 is a block schematic of an exemplary network node 815, inaccordance with certain embodiments. Network node 815 may be any type ofradio network node or any network node that communicates with a wirelessdevice 810 and/or with another network node 815. Network nodes 815 maybe deployed throughout network 800 as a homogenous deployment,heterogeneous deployment, or mixed deployment. A homogeneous deploymentmay generally describe a deployment made up of the same (or similar)type of network nodes 815 and/or similar coverage and cell sizes andinter-site distances. A heterogeneous deployment may generally describedeployments using a variety of types of network nodes 815 havingdifferent cell sizes, transmit powers, capacities, and inter-sitedistances. For example, a heterogeneous deployment may include aplurality of low-power nodes placed throughout a macro-cell layout.Mixed deployments may include a mix of homogenous portions andheterogeneous portions.

As depicted, network node 815 may include one or more of transceiver1010, processor 1020, memory 1030, and network interface 1040. In someembodiments, transceiver 1010 facilitates transmitting wireless signalsto and receiving wireless signals from wireless device 810 (e.g., via anantenna), processor 1020 executes instructions to provide some or all ofthe functionality described above as being provided by a network node815, memory 1030 stores the instructions executed by processor 1020, andnetwork interface 1040 communicates signals to backend networkcomponents, such as a gateway, switch, router, Internet, Public SwitchedTelephone Network (PSTN), core network nodes or radio networkcontrollers, etc.

In certain embodiments, network node 815 may be capable of usingmulti-antenna techniques, and may be equipped with multiple antennas andcapable of supporting Multiple Input Multiple Output (MIMO) techniques.The one or more antennas may have controllable polarization. In otherwords, each element may have two co-located sub elements with differentpolarizations (e.g., 90 degree separation as in cross-polarization), sothat different sets of beamforming weights will give the emitted wavedifferent polarization.

Processor 1020 may include any suitable combination of hardware andsoftware implemented in one or more modules to execute instructions andmanipulate data to perform some or all of the described functions ofnetwork node 815. In some embodiments, processor 1020 may include, forexample, one or more computers, one or more central processing units(CPUs), one or more microprocessors, one or more applications, and/orother logic.

Memory 830 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by a processor. Examples of memory 830 includecomputer memory (for example, Random Access Memory (RAM) or Read OnlyMemory (ROM)), mass storage media (for example, a hard disk), removablestorage media (for example, a Compact Disk (CD) or a Digital Video Disk(DVD)), and/or or any other volatile or non-volatile, non-transitorycomputer-readable and/or computer-executable memory devices that storeinformation.

In some embodiments, network interface 1040 is communicatively coupledto processor 1020 and may refer to any suitable device operable toreceive input for network node 815, send output from network node 815,perform suitable processing of the input or output or both, communicateto other devices, or any combination of the preceding. Network interface1040 may include appropriate hardware (e.g., port, modem, networkinterface card, etc.) and software, including protocol conversion anddata processing capabilities, to communicate through a network.

Other embodiments of network node 815 may include additional componentsbeyond those shown in FIG. 12 that may be responsible for providingcertain aspects of the radio network node's functionality, including anyof the functionality described above and/or any additional functionality(including any functionality necessary to support the solutionsdescribed above). In certain embodiments, for example, network node 815may include components for performing the reception method discussedabove with regard to FIG. 3 and/or the transmission method discussedabove with regard to FIG. 5. The various different types of networknodes may include components having the same physical hardware butconfigured (e.g., via programming) to support different radio accesstechnologies, or may represent partly or entirely different physicalcomponents.

FIG. 13 is a block schematic of an exemplary radio network controller orcore network node 1100, in accordance with certain embodiments. Examplesof network nodes can include a mobile switching center (MSC), a servingGPRS support node (SGSN), a mobility management entity (MME), a radionetwork controller (RNC), a base station controller (BSC), and so on.The radio network controller or core network node 1100 include processor1120, memory 1130, and network interface 1140. In some embodiments,processor 1120 executes instructions to provide some or all of thefunctionality described above as being provided by the network node,memory 1130 stores the instructions executed by processor 1120, andnetwork interface 1140 communicates signals to any suitable node, suchas a gateway, switch, router, Internet, Public Switched TelephoneNetwork (PSTN), network nodes 115, radio network controllers or corenetwork nodes, etc.

Processor 1120 may include any suitable combination of hardware andsoftware implemented in one or more modules to execute instructions andmanipulate data to perform some or all of the described functions of theradio network controller or core network node. In some embodiments,processor 1120 may include, for example, one or more computers, one ormore central processing units (CPUs), one or more microprocessors, oneor more applications, and/or other logic.

Memory 1130 is generally operable to store instructions, such as acomputer program, software, an application including one or more oflogic, rules, algorithms, code, tables, etc. and/or other instructionscapable of being executed by a processor. Examples of memory 1130include computer memory (for example, Random Access Memory (RAM) or ReadOnly Memory (ROM)), mass storage media (for example, a hard disk),removable storage media (for example, a Compact Disk (CD) or a DigitalVideo Disk (DVD)), and/or or any other volatile or non-volatile,non-transitory computer-readable and/or computer-executable memorydevices that store information.

In some embodiments, network interface 1140 is communicatively coupledto processor 1120 and may refer to any suitable device operable toreceive input for the network node, send output from the network node,perform suitable processing of the input or output or both, communicateto other devices, or any combination of the preceding. Network interface1140 may include appropriate hardware (e.g., port, modem, networkinterface card, etc.) and software, including protocol conversion anddata processing capabilities, to communicate through a network.

Other embodiments of the network node may include additional componentsbeyond those shown in FIG. 13 that may be responsible for providingcertain aspects of the network node's functionality, including any ofthe functionality described above and/or any additional functionality(including any functionality necessary to support the solution describedabove).

According to certain embodiments, a user equipment is provided for usein a cellular network. The user equipment may include a transceiver, aprocessor, and a memory. The user equipment may be configured to acquirea Demodulation Reference Signal (DMRS) configuration. A mapping isdetermined from the DMRS configuration to a phase noise trackingreference signal (PNT-RS). A channel estimate is performed using theDMRS configuration. Phase noise estimation and compensation is performedbased on the PNT-RS by using the mapping and the channel estimate.

According to certain embodiments, a method by a user equipment isprovided for use in a cellular network. The method includes acquiring aDemodulation Reference Signal (DMRS) configuration. A mapping isdetermined from the DMRS configuration to a phase noise trackingreference signal (PNT-RS). A channel estimate is performed using theDMRS configuration. Phase noise estimation and compensation is performedbased on the PNT-RS by using the mapping and the channel estimate.

According to certain embodiments, a user equipment is provided for usein a cellular network. The user equipment includes a transceiver, aprocessor, and a memory. The user equipment is configured to send aDemodulation Reference Signal (DMRS) configuration. The DMRSconfiguration is associated with a mapping to a PNT-RS transmission. APNT-RS is transmitted to the receiver according to the mapping.

According to certain embodiments, a method by a user equipment isprovided for use in a cellular network. The method includes sending aDemodulation Reference Signal (DMRS) configuration. The DMRSconfiguration is associated with a mapping to a PNT-RS transmission. APNT-RS is transmitted to the receiver according to the mapping.

According to certain embodiments, a network node is provided for use ina cellular network. The network node includes a transceiver, aprocessor, and a memory. The network node is configured to acquire aDemodulation Reference Signal (DMRS) configuration. A mapping isdetermined from the DMRS configuration to a phase noise trackingreference signal (PNT-RS). A channel estimate is performed using theDMRS configuration. Phase noise estimation and compensation is performedbased on the PNT-RS by using the mapping and the channel estimate.

According to certain embodiments, a method by a network node is providedfor use in a cellular network. The method includes acquiring aDemodulation Reference Signal (DMRS) configuration. A mapping isdetermined from the DMRS configuration to a phase noise trackingreference signal (PNT-RS). A channel estimate is performed using theDMRS configuration. Phase noise estimation and compensation is performedbased on the PNT-RS by using the mapping and the channel estimate.

According to certain embodiments, a network node is provided for use ina cellular network. The network node includes a transceiver, aprocessor, and a memory. The network node is configured to send aDemodulation Reference Signal (DMRS) configuration. The DMRSconfiguration is associated with a mapping to a PNT-RS transmission. APNT-RS is transmitted to the receiver according to the mapping.

According to certain embodiments, a method by a network node is providedfor use in a cellular network. The method includes sending aDemodulation Reference Signal (DMRS) configuration. The DMRSconfiguration is associated with a mapping to a PNT-RS transmission. APNT-RS is transmitted to the receiver according to the mapping.

According to certain embodiments, a method by a receiver is provided foruse in a cellular network. The method includes acquiring a DemodulationReference Signal (DMRS) configuration. A mapping to a PNT-RStransmission from the DMRS configuration is determined. A channelestimate is performed using the DMRS configuration. Phase noiseestimation and compensation is performed based on the PNT-RS by usingthe mapping and the channel estimate.

According to certain embodiments, a receiver is provided for use in acellular network. The receiver includes a transceiver, a transmitter, aprocessor, and a memory. The receiver is configured to acquire aDemodulation Reference Signal (DMRS) configuration and determine amapping to a PNT-RS transmission from the DMRS configuration. A channelestimate is performed using the DMRS configuration. Phase noiseestimation and compensation is performed based on the PNT-RS, using themapping and the channel estimate.

According to certain embodiments, a method by a transmitter is provided.The method includes sending, by the transmitter, a DemodulationReference Signal (DMRS) configuration. The DMRS configuration beingassociated with a mapping to a PNT-RS transmission. A PNT-RS istransmitted to the receiver according to the mapping.

According to certain embodiments, a transmitter is provided for use in acellular network. The transmitter includes a transceiver, a transmitter,a processor, and a memory. The transmitter is configured to send aDemodulation Reference Signal (DMRS) configuration, the DMRSconfiguration being associated with a mapping to a PNT-RS transmission.A PNT-RS is transmitted to the receiver according to the mapping.

Certain embodiments of the present disclosure may provide one or moretechnical advantages. For example, in certain embodiments, overhead maybe reduced for the transmission of the PNT-RS signal for the use-casewith a multi-antenna receiver in uplink or downlink. Consider, forexample, an uplink (UL) or downlink (DL) Multi-User Multiple

Input Multiple Output (MU-MIMO) with four or more receiver antennas. Iffour users are multiplexed, four sub-carriers may be used. For example,each user may transmit on one sub-carrier and blank the other threesub-carriers. Alternatively, according to the methods described herein,only one sub-carrier may be used and the PNT-RS may be separated usingthe DMRS channel estimate. Accordingly, a technical advantage of certainembodiments may include an overhead reduction of up to seventy-fivepercent. Even where some interference remains and gain is lowered, anoverhead reduction may be expected.

Modifications, additions, or omissions may be made to the systems andapparatuses described herein without departing from the scope of thedisclosure. The components of the systems and apparatuses may beintegrated or separated. Moreover, the operations of the systems andapparatuses may be performed by more, fewer, or other components.Additionally, operations of the systems and apparatuses may be performedusing any suitable logic comprising software, hardware, and/or otherlogic. As used in this document, “each” refers to each member of a setor each member of a subset of a set.

Modifications, additions, or omissions may be made to the methodsdescribed herein without departing from the scope of the disclosure. Themethods may include more, fewer, or other steps. Additionally, steps maybe performed in any suitable order.

Although this disclosure has been described in terms of certainembodiments, alterations and permutations of the embodiments will beapparent to those skilled in the art. Accordingly, the above descriptionof the embodiments does not constrain this disclosure. Other changes,substitutions, and alterations are possible without departing from thespirit and scope of this disclosure, as defined by the following claims.

1. A user equipment for use in a cellular network, the user equipmentcomprising a transceiver, a processor, and a memory, the user equipmentconfigured to: acquire a Demodulation Reference Signal (DMRS)configuration; determine a mapping from the DMRS configuration to aphase noise tracking reference signal (PNT-RS); perform a channelestimate using the DMRS configuration; and perform phase noiseestimation and compensation, based on the PNT-RS, using the mapping andthe channel estimate.
 2. The user equipment of claim 1, whereindetermining the mapping comprises mapping the PNT-RS to a specific DMRSport.
 3. The user equipment of claim 1, wherein the phase noiseestimation and compensation is based on a PNT-RS receiver setting, whichis based on the mapping and the channel estimate.
 4. The user equipmentof claim 1, wherein the DMRS configuration is acquired based on a DMRStransmitted by the cellular network.
 5. The user equipment of claim 1,wherein the channel estimate is calculated using the DMRS configuration.6. The user equipment of claim 1, wherein the DMRS occupies a greaternumber of subcarriers per subframe than the PNT-RS, and wherein thePNT-RS occupies a greater number of OFDM symbols per subframe than theDMRS.
 7. The user equipment claim 1, wherein the DMRS occupies aplurality of subcarriers that are separated by a plurality of othersubcarriers, and wherein the PNT-RS occupies a plurality of successiveOFDM symbols.
 8. The user equipment of claim 7, wherein the DMRSoccupies two or more sets of adjacent subcarriers, each set of adjacentsubcarriers separated by a plurality of other subcarriers, and whereinthe PNT-RS occupies a plurality of successive OFDM symbols not occupiedby the DMRS. 9.-15. (canceled)
 16. A method by a user equipment for usein a cellular network, the method comprising: acquiring a DemodulationReference Signal (DMRS) configuration; determining a mapping from theDMRS configuration to a phase noise tracking reference signal (PNT-RS);performing a channel estimate using the DMRS configuration; andperforming phase noise estimation and compensation, based on the PNT-RS,using the mapping and the channel estimate.
 17. The method of claim 16,wherein determining the mapping comprises mapping the PNT-RS to aspecific DMRS port.
 18. The method of claim 16, wherein the phase noiseestimation and compensation is based on a PNT-RS receiver setting, whichis based on the mapping and the channel estimate.
 19. The method ofclaim 18, wherein the DMRS configuration is acquired based on a DMRStransmitted by the cellular network.
 20. The method of claim 16, whereinthe channel estimate is calculated using the DMRS configuration.
 21. Themethod of claim 16, wherein the DMRS occupies a greater number ofsubcarriers per subframe than the PNT-RS, and wherein the PNT-RSoccupies a greater number of OFDM symbols per subframe than the DMRS.22. The method of claim 16, wherein the DMRS occupies a plurality ofsubcarriers that are separated by a plurality of other subcarriers, andwherein the PNT-RS occupies a plurality of successive OFDM symbols. 23.The method of claim 22, wherein the DMRS occupies two or more sets ofadjacent subcarriers, each set of adjacent subcarriers separated by aplurality of other subcarriers, and wherein the PNT-RS occupies aplurality of successive OFDM symbols not occupied by the DMRS. 24.-40.(canceled)
 41. A network node for use in a cellular network, the networknode comprising a transceiver, a processor, and a memory, the networknode configured to: acquire a Demodulation Reference Signal (DMRS)configuration; determine a mapping from the DMRS configuration to aphase noise tracking reference signal (PNT-RS); perform a channelestimate using the DMRS configuration; and perform phase noiseestimation and compensation, based on the PNT-RS, using the mapping andthe channel estimate. 42.-55. (canceled)
 56. A method by a network nodefor use in a cellular network, the method comprising: acquiring aDemodulation Reference Signal (DMRS) configuration; determining amapping from the DMRS configuration to a phase noise tracking referencesignal (PNT-RS); performing a channel estimate using the DMRSconfiguration; and performing phase noise estimation and compensation,based on the PNT-RS, using the mapping and the channel estimate.57.-108. (canceled)